<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <title>搜索框demo</title>
  <style type="text/css">
    * {
      margin: 0;
      padding: 0;
    }

    body {
      width: 100vw;
      height: 100vh;
      background: radial-gradient(at center,
          #3498db, #2980b9);
      display: flex;
      justify-content: center;
      align-items: center;
    }

    div.search {
      height: 40px;
      width: 500px;
    }

    div.search form {
      width: 100%;
      height: 100%;
    }

    div.search form input:nth-child(2) {
      width: 400px;
      height: 100%;
      font-size: 16px;
      text-indent: 40px;
      border: none;
      float: left;
    }

    div.search form input:nth-child(3) {
      width: 100px;
      height: 100%;
      font-size: 16px;
      letter-spacing: 5px;
      border: none;
    }

    div.search form img {
      position: absolute;
      left: 50vw;
      transform: translateX(-250px);
      margin-top: 10px;
      margin-left: 10px;
      height: 20px;
    }


    div.search {
      height: 40px;
      width: 500px;
    }

    div.search form {
      width: 100%;
      height: 100%;
    }

    div.search form input:nth-child(2) {
      width: 400px;
      height: 100%;
      font-size: 16px;
      text-indent: 40px;
      border: none;
      float: left;
    }

    div.search form input:nth-child(3) {
      width: 100px;
      height: 100%;
      font-size: 16px;
      letter-spacing: 5px;
      border: none;
    }

    div.search form img {
      position: absolute;
      left: 50vw;
      transform: translateX(-250px);
      margin-top: 10px;
      margin-left: 10px;
      height: 20px;
    }
  </style>
</head>

<body>
  <div class="search">
    <form>
      <img src="./search_ico.png" alt="">
      <input type="text" name="condition" placeholder="请输入搜索条件">
      <input type="submit" value="搜索">
    </form>
  </div>
</body>

</html>